Wood sanding machine drawings. Belt grinding machine: study and do it yourself

Grinder (English) literally – crusher. Meat grinder is a meat grinder, rock (stone) grinder is a stone crusher; stick (wood) grinder – garden crusher of branches and twigs into chips. But there is also a completely unambiguous meaning of the word grinder: in mechanical engineering and metalworking it is grinding machine. A useful household item. For example, it is impossible to guide a dull meat grinder knife on a whetstone manually. On a manual knife sharpener - somehow possible, having solid working skills. And on the grinder - no problem. The same thing - if you need to polish a part complex shape without disturbing her profile. Either just sharpen the scissors or professional knife. It is best to edit various types of wood and metal cutters on a grinder. It is quite possible to design and assemble a grinder with your own hands, without having complex equipment and skills to work with it. In terms of money, this will mean savings of 50-90 thousand rubles. up to 3-6 thousand USD.

To make a grinder yourself, you will need to order a maximum of 4-5 turned parts, and it is often possible to do without external turning at all. For example, how to make a simple grinder literally out of trash, see the video below:

Video: DIY belt grinder made from trash

Or another option, how to make a stronger and more durable grinder from scrap metal:

Video: scrap metal grinder

Disc or tape? And drive

There are almost more types of grinding machines used in industry than lathes. The emery known to all craftsmen - a motor with a pair of grinding wheels (or one wheel) - is also a grinder. For yourself at home, it makes sense to make either a disk end grinder (plate grinder) or a belt grinder. In the first, the abrasive is applied to a rotating hard disk; in the second - on an elastic band running around a system of pulleys and rollers. Disc is more suitable for grinding simple wooden parts and coarse or medium purity - metal. Using a belt grinder, it is also possible to produce precise and clean finishing of profiled parts of complex shapes, incl. large-sized, see below.

A disk grinder is very easily obtained from the same emery or a motor of suitable power, see below. You need to order an adapter from the electric motor shaft to the shank of a metal-based grinding disc. Or under chuck, then on the same motor it will be possible to build a mini lathe, see figure:

A worn-out “plate” is suitable: a disk made of thin (4-6 mm) fibrous plastic is glued to the edge of its side, and an abrasive is placed on it. How to make an end grinder, see next. video clip.

Video: homemade end grinder

The difference between a disk and tape grinder is not only in the possibilities of use. If we take ordinary household crafts, then for a disk grinder a drive power of 250-300 W on the shaft is enough. For small wooden parts - and 150-170 W. This is the motor from the old one washing machine, straight (regular) drill or screwdriver. But for a belt grinder you will need an engine from 450-500 W: three-phase with batteries of starting and operating capacitors. If you plan to process large items, then the motor power is from 1-1.2 kW. Moreover, capacitor batteries for both will cost not much less than the engine itself.

Note: a 100-200 W drive uses a mini-belt grinder (see below) for precise knife dressing, grinding/polishing jewelry, etc.

A drill or screwdriver as a grinder drive is also convenient in that it allows you to quickly change the speed of movement of the abrasive (see below) using a standard speed controller. You just need, firstly, to make a holder for the drill that rigidly fixes the tool. Secondly, an elastic transition coupling from the drill to the disk shank, because It is difficult to achieve their precise alignment without special equipment, and runout will negate the accuracy of processing and can damage the drive tool.

Drawings of a drill holder for using it as a drive for a home metal-cutting machine are given on the left in the figure:

Since shock and irregular alternating loads on the drive in a grinder are an order of magnitude lower than, say, in lathe, the drill holder for it can be made of hard wood, plywood, chipboard, MDF, on the right in Fig. The diameter of the mounting (large) hole is along the neck of the drill. It is highly advisable to use a drill without an impact mechanism and with a steel shell on the neck (for installing the front handle).

coupling

For the adapter coupling, you will need a piece of steel rod (not necessarily turned) of the same diameter as the shank of the grinder drive shaft, and a piece of reinforced PVC hose and (garden irrigation) with a gap such that it stretches tightly over the rod and shank. The length of the “free” hose (between the ends of the rod and the shank in it) is 3-5 cm. The length of the protruding part of the rod should be sufficient for reliable clamping in the drill chuck. After assembling the coupling in place, the hose on the shank and rod is tightened tightly with clamps; can be wired. Such a coupling completely counteracts the misalignment of the drive and driven shaft up to 1-1.5 mm.

Tape is still better

A belt grinder allows you to do everything a disk grinder can do, and much more. Therefore, next we will focus on how to make a belt sanding machine with your own hands. Amateurs, focusing on industrial designs, sometimes make very intricate grinders, see figure:

And this is justified: the design and kinematics of the belt grinder are very flexible, which makes it possible to successfully use scrap materials and old scrap metal. You just need to follow 3 principles:

Do not do as in the second photo from the left: the abrasive side of the tape should only touch the workpiece. Otherwise, the abrasive will eat both the guide rollers and itself. The accuracy and cleanliness of processing during one work operation will be unpredictable;
The design of the machine must ensure uniform tension of the belt, regardless of the nature of the operation performed;
The speed of the belt must correspond to the nature of the operation being performed.

Kinematics and design

As mentioned above, there are many designs of grinders. When considering what and how to build a grinder for yourself, it is better to focus on industrial designs designed to be fully mechanized for precise and clean grinding of large-sized profiled parts: once it “sands” the blade of an airplane propeller or wind turbine properly, it can handle any other work.

Kinematic diagrams of grinders for the specified purpose are shown in Fig.:

Basic kinematic diagrams of belt grinding machines (grinders)

Pos. A is the most complex and perfect, with three rocker arms. If the length of the tension roller rocker arm is approx. 2 times less than the working one, then by adjusting the tension of the springs, it is possible to achieve uniform tension of the tape when the working rocker moves 20-30 degrees up and down. By tilting the bypass rocker, firstly, the machine is reconfigured for the belts different lengths. Secondly, in the same way you can quickly change the belt tension for different operations. The working branch of the belt can be any, except for the one running from the drive pulley to the tension roller, i.e. A grinder with 3 rocker arms is both horizontal and vertical.

The scheme with a coaxially swinging rocker arm (item 2) is simpler, cheaper and in terms of processing accuracy is not inferior to the previous one, if the length of the rocker arm between the axes is at least 3 diameters of the workpiece. To reduce the profile by grinding, the stroke of the rocker arm is limited by stops within 10 degrees up and down. The pressure of the belt to the part is most often gravitational, under the weight of a rocker arm with a bypass pulley. The tension of the belt can be quickly changed within certain limits by pulling the rocker up with a weak adjustable spring, partly compensating for its heaviness. The grinder of this design can work as a grinder for small parts from a sliding table. In this case, the rocker arm is rigidly fixed horizontally, and the working surface of the belt will run around the bypass pulley. For example, the fairly popular BTS50 grinder is made using a coaxial rocker design. The disadvantages of the scheme are, firstly, the technologically complex rocker arm joint, which is coaxial with the drive shaft. Secondly, the need for an elastic band: if you make the idler pulley sliding and spring-loaded, the processing accuracy decreases. This drawback when processing small parts is completely eliminated by an additional tension roller, see below.

The scheme with one misaligned rocker arm is used quite rarely in industry, because in principle, it does not allow achieving uniform tape tension. However, it gives accuracy that is quite sufficient at home and allows you to build a very good simple grinder.

What's good for what?

Now let's see what is possible to “squeeze” out of this or that circuit from the point of view of an amateur master. And then we’ll try to figure out how to make a grinder belt ourselves and do without custom-made turned parts.

3 rocker arms

Competent amateurs build their grinders exactly according to the scheme with 3 rocker arms, on the left in Fig. below. Not all propeller blades can be ground, but in this case another advantage of this scheme applies: if the grinder is used as a vertical grinder, then the working branch of the belt is elastic. This allows to a skilled craftsman, let's say, point cutting edges and blades with literally micron precision.

In industrial grinders for home use, the 3-rocker design is also widely used (in the center) for the same reasons. Repeating them yourself in most cases is quite possible. For example, the drawings of the KMG grinder, popular abroad, can be downloaded.

The dimensions are, however, inch - the machine is American. For the drive, in any case, it is possible to use an angle drill-grinder (on the right in the figure, it is quite suitable in terms of power) with homemade pulley and rollers, see below.

Note: if you are making a stationary drive, try to get an asynchronous motor at 2-3 speeds from an unusable washing machine with a horizontal tank. Its advantage is low speed. This makes it possible to make a drive pulley large diameter and thereby prevent the tape from slipping. A belt slip during operation is almost certainly a damaged part. Most washing machines have 2-3 speed asynchronous motors for 220 V - Spanish. Shaft power – 600-1000 W. If you come across one, don't forget about the standard phase-shifting capacitor bank.

Coaxial rocker

Amateurs do not make pure grinders with a coaxial rocker arm. A coaxial hinge is a complicated thing; you can’t make an elastic band yourself, and store-bought ones are expensive. Grinders with a coaxial rocker are most often used at home in the version for small precision work from the table, i.e. with a rigidly fixed horizontal rocker arm. But then the need for a rocker arm as such disappears.

An example is a mini grinder, the drawings of which are given in the figure:

Its features are, firstly, an overhead bed for the tape (item 7), which significantly expands the possibilities of use. For example, the plane iron is straightened on this grinder with an angular stop literally by itself. IN in this case the grinder works, so to speak, like a self-propelled whetstone (emery block). Having removed the bed, we get a grinder with an elastic band for precise grinding/polishing of rounded small parts. Secondly, the tension shaft (item 12). By clamping it to the groove with nuts, we get a relatively fixed tension of the tape for working with the bed. And having released the nuts, we switch the grinder to the gravitational belt tension mode for fine work. Drive - not necessarily through a pulley (pos. 11). You can screw it directly onto the drive shaft shank (item 16) from the drill through the adapter coupling, see above.

A specialized tool grinder (for example, for guiding and straightening turning tools) generally loses any semblance of the original design. A high-speed motor is used for it (200-300 W is enough power). The drive pulley is, accordingly, of small diameter. The bypass pulley, on the contrary, is made larger and heavier for inertia. All this together helps reduce tape runout. The tension roller for the same purpose, plus for greater uniformity of belt tension, is moved further away and spring-loaded with a long, not very strong spring. How to make a grinder for processing incisors, see the video below.

Video: grinder for making cutters

One rocker

In amateur practice, grinders with a misaligned rocker arm are good because they do not require precise parts at all. For example, hinges can be made from card loops. At the same time, the processing accuracy remains sufficient for ordinary amateur requests.

In this case, the original scheme is also modified: the rocker arm is turned 90 degrees, moved up and spring-loaded, on the left in Fig. It turns out to be a simple vertical grinder. And, importantly, it works without problems with homemade non-stretchable tape. A tension spring (in the center) or a compression spring can provide tension to the tape. Its strength is not so important, as long as the tape does not bend excessively during operation. No adjustments are required during use.

Consumables and parts

The only consumable material for a belt grinder is a tape (not counting grease for bearings and hinges. The tape can be ordered to the desired length (see at the end), but you can also make it yourself from sandpaper on textile based. It is highly desirable - flexible, unimpregnated. In general, the procedure for making a grinder belt with your own hands is as follows:

We cut the workpiece - a strip of the required length and width.
We prepare a mandrel (not necessarily round) with a length along the generatrix slightly less than the length of the tape.
We outline the mandrel with the workpiece inside out.
We bring the ends of the workpiece exactly end to end and securely fasten them.
Place a piece of glue stick for a hot glue gun on the joint.
Heat with a construction hairdryer until the glue melts.
We apply a patch of thin fabric to the joint.
Press with something hard through the Teflon film until the glue hardens.

There are three significant points here. The first is to use a rough PET film with a thickness of 25-50 microns (sold) instead of fabric for the patch. It is very durable, but just try running your finger across a PET bottle. Not very slippery? Rough PET film cannot be stretched under tension even over polished metal. And instead of a patch, it is better to seal the back of the tape with a continuous strip of PET film with an overlap of 2-3 cm. The runout of the tape will be no more than 0.05-0.1 mm. This is less than from the thinnest calico and even less than the error in the thickness of the blank skin.

Second, insert the finished tape into the machine and grind something indecent with it without strong pressure. The scar on the seam will be sealed, and the tape will become no worse than the branded one.

But the most important thing is elasticity best glue for gluing the grinder tape, it is not expensive and difficult to use thermo- or mounting, but ordinary PVA. If the tape is covered with a lining along the entire length of the back, then its PVA strength will be more than enough. How to glue PVA grinder tape, see video

Video: gluing grinder tape with PVA glue

Pulley

Formative ( side surface cross-section) of the grinder drive pulley should be straight. If you use a barrel pulley, the belt will bend like a trough along its entire length. The rollers prevent it from slipping, see below, but the generatrix of the pulley must be straight.

A pulley for a grinder that is not intended for particularly precise work, firstly, does not have to be turned. In a scheme with 3 rocker arms, the beating of the belt from its misalignment will go out on the rollers before it reaches the working branch. In a simple vertical grinder, the beating of the belt will be sufficiently damped by the tension spring. Therefore, it is quite possible to make a pulley for a grinder without a machine, see video:

Video: drive wheel on a grinder without a lathe

Secondly, the pulley, rollers and, in general, all the parts of a home grinder can be made from plywood. In production, this is certainly not an option, even if a plywood grinder is offered for free with an additional payment: the grinder needs a salary, and the wooden grinder in the workshop will completely wear out before it pays for it and itself. But you won’t be running a grinder at home every day in 3 shifts. And no tape slips along the plywood pulley. Incl. homemade. So you can safely make a grinder pulley from plywood:

Video: pulley for grinder made of plywood

It is much more important to correctly calculate the diameter of the pulley based on the engine speed and the required belt speed. A running belt that is too slow will tear the material being processed; too fast - it will erase itself without really processing anything. In which case, what tape speed is needed is a separate conversation, and a very difficult one. In general, the finer the abrasive and harder the material being processed, the faster the belt should move. How the belt speed depends on the diameter of the pulley and motor speed, see figure:

Fortunately, for most abrasive-material pairs permissible limits The belt speeds are quite wide, so choosing a pulley for the grinder can be easier:

Video: what wheel is needed for a belt grinder

Rollers

The rollers of the grinder, oddly enough at first glance, are its most important parts. It is the rollers that keep the tape from slipping and ensure its uniform tension across the width. Moreover, there can be only one video in kinematics, see, for example, the video above about the grinder for incisors. Only barrel rollers can cope with this task, see below. But the “trough” of the belt after any roller must straighten before it reaches the working area.

Rollers with flanges (sides, edges) will not hold the tape. The issue here is not only and not so much with the misalignment of the roller axes: the grinder belt, unlike the drive belt, must withstand the loads from the parts being processed without slipping. If you make videos with flanges, then if you barely touch the tape with something, it will creep onto the flange. In the grinder you need to use Type 3 barrel rollers (highlighted in red on the left in the figure).

The dimensions of Type 3 rollers are also given there. It is advisable to take the diameter of the rollers no more than 0.5 of the width of the tape (so that the “trough” does not go far), but not less than 20 mm for turned steel and not less than 35-40 mm for plywood. The tension roller (the probability of the tape slipping from it is greatest), if the working branch of the tape does not come off it, can have a diameter of 0.7-1.2 its width. Plywood rollers are made in the form of a thick shell into which the bearing is pressed; then the roller is mounted on the axle (in the center in the figure) and processed cleanly, see e.g. track. video:

Video: barrel roller for grinder

Not every turner can turn a profile roller barrel exactly according to GOST even on a machine. Meanwhile, there is a way to make videos for the grinder without significant difficulties. The same PVC-reinforced garden hose will help out, on the right in Fig. previously. A section of it is pulled tightly onto a roller blank with a straight generatrix and cut off with a margin along the edges to the thickness of the hose wall. The result is a roller with a complex profile of the generatrix, which holds the tape even better and gives it a smaller “trough”. Don't believe me? Try to get to an airplane or missile graveyard and dig around in them. You will find rollers with exactly the same generatrix profile. It’s just that mass production of complex profile rollers is much more expensive than Type 3 barrels.

And another option

All critical parts of the grinder - a solid belt, pulleys with a coating that prevents it from slipping, rollers - can be purchased separately. They won’t be that cheap, but still not thousands of foreign ones and not dozens of native leather jackets. The remaining parts of the grinder, either flat or from corrugated pipes, are made using a regular tabletop drill or drill. Here's where you can order parts for the grinder:

//www.cora.ru/products.asp?id=4091 – tape. Lengths and widths are made according to the customer's wishes. Consult on abrasives and processing modes. Prices are reasonable. Delivery time - questions to Ruposhta.
//www.equipment.rilkom.ru/01kmpt.htm – spare parts (components) for grinding machines. There is everything, the prices are divine. Delivery - see previous page.
//www.ridgid.spb.ru/goodscat/good/listAll/104434/ – the same, but foreign made. Prices are higher, delivery is the same.
//www.pk-m.ru/kolesa_i_roliki/privodnye_kolesa/ – drive wheels. You can find ones suitable for grinding.
//dyplex.by.ru/bader.html, //www.syndic.ru/index.php?option=com_content&task=view&id=36&Itemid=36 – spare parts for grinders. They do not make ribbons to order - choose from the catalogue. Rollers without axles; axles sold separately. The quality is impeccable, but everything is very expensive. Dispatch - within 2 weeks to the border. Then - their customs, our customs, Rusposhta. Total approx. 2 months It may not arrive if some local bureaucrat considers the product sanctioned. In this case, there are no problems with the return of payment due to the complete absence of real opportunities for the average citizen to receive one.

5,00

One of the main methods of processing wood (after cutting, of course) is sanding. Manual method known for a long time - wooden block is wrapped in sandpaper, and with the help of such a simple device the workpiece is given the required shape.

The method is unproductive and requires considerable physical effort. Craftsmen who work with wood regularly use small-scale mechanization.

Types of grinding machines

There are a variety of ready-made devices on sale that can be used to process wooden workpieces of any size. To understand the mechanism of operation, consider some of them:

Based on the name, the working surface is made in the form of a disk.

The design is quite simple - a circle with good rigidity is put on the axis of the electric motor. The outer surface has a Velcro-like coating on which it is attached sandpaper. No gearboxes or drive mechanisms are required. The grinding force is small, the rotor axis can handle the load quite well.

A hand rest is installed in the transverse plane, at the level of the center of the disk. It can have a hinged mount, which allows you to process workpieces at a fixed angle.

A feature of disk machines is the adjustment of processing speed without changing the number of axis revolutions. You simply move the workpiece along the radius of the circle. At a uniform angular velocity, the linear velocity at the periphery is higher.

A strip of sandpaper, joined into a continuous strip, is stretched between two shafts.

Moreover, in work area does not sag under workpiece pressure. A persistent working plane made of material with a low coefficient of friction is installed under the tape. By pressing the material being processed to the plane, the operator receives an endless abrasive surface.

The quality and ease of processing cannot be compared with manual tools. For mass production wooden products, such a sled is an indispensable attribute of any workshop.

The main feature is the predictable result throughout the entire plane. You can level the ends of a sufficiently long length.

The working surface can be horizontal or vertical, as well as the direction of movement of the belt.

Such a device can be classified as a grinding unit with some stretch. The main application is horizontal leveling of planes using the jointer method.

The principle of operation is as follows: sandpaper is attached to one or two drums. The most common method is spiral winding. Below, under the drum, there is a flat table. The distance between the processing surface and the table is adjustable. By setting a fixed height, you can calibrate products of the same type, leveling the thickness of the workpieces.

Two-in-one grinding machine

To save space (and money), manufacturers often combine two types of fixtures in one design.

This not only reduces purchasing costs, but also improves ease of use. When processing one part, you can take advantage of two grinding units at once: disk and belt. In this case, one engine is used, and the load on it does not increase much.

Rotation on drive shaft band press transmitted from an electric motor, which is connected to it using a belt drive. The speed of movement of the belt mechanism can be adjusted, thereby changing the processing modes of parts. The belt of a surface grinding machine can be positioned horizontally or vertically, as well as at a certain angle, which is allowed by some models of equipment in this category.

When choosing a belt sanding machine model for processing a particular part, it is important to consider the length of the surface that needs to be sanded. It is much more convenient to process parts on such machines whose surface length is less than the length abrasive tape and desktop. If such conditions are met, the quality of processing will be much higher.

The belt grinding machine can have different designs: with a movable and fixed work table, with a free belt. A separate category includes wide-belt equipment, the peculiarity of which is that their work table, which is also a feed element, is made in the shape of a caterpillar. In those equipment models that have a work table in their design, the abrasive belt is located in a horizontal plane, and in equipment with a free belt that does not have a work table, it can have a different spatial position.

Compulsory structural element any belt sander, including tabletop ones, is exhaust device, which is necessary to remove dust generated in large quantities during the processing process. Both a professional and any homemade grinding machine used in a home workshop or garage are powered by electric motor.

Principle of operation

The main operating parameters of a belt sanding machine include the feed speed and the force with which the belt is pressed against the workpiece. Parameters such as the degree of grain size of the abrasive belt should be selected depending on the material from which the workpiece is made, as well as the degree of roughness that the surface of the machined product should have.

The characteristics of the material being processed, in particular its hardness, primarily influence the grit size of the abrasive belt to be selected. Processing modes that are directly related to each other are feed speed and tape clamping force. So, if grinding is carried out at high speed, but with insignificant pressing force of the abrasive tape, then some areas of the surface of the part may turn out to be untreated. If, on the contrary, you increase the clamping force and reduce the feed speed, then you may encounter the fact that separate areas burns and blackening of the material may appear on the treated surface.

Another variation of the machine - view from the working surface of the belt

The results of grinding are also influenced by how well the abrasive tape is glued together. To obtain high quality To avoid problems with the belt machine, do not use abrasive belts that are not glued correctly or have torn edges. When putting the tape on the equipment shafts, it should be positioned so that the overlapping end of the seam does not ride up against the surface of the workpiece, but slides along it. Learn more about gluing tape in the video below.

Any, including a manual grinding machine, must provide the ability to adjust the belt tension, which is ensured by moving a movable shaft that is not driven. Tape tension is a very important parameter, when choosing which you should follow the “golden mean” rule. If the sanding machine belt is pulled too tightly, this can lead to its rupture during operation, and if its tension is too weak, it causes slipping and, as a result, its excessive heat. The main characteristic for determining the degree of tension of the tape is its deflection, which is measured by lightly pressing on its surface in a tense state.

A manual belt grinding machine can be serviced by one operator, who moves the work table with the workpiece and rotates it so as to bring all areas of its surface under the abrasive belt.

How to make a belt sander

Many home craftsmen and professionals are wondering how to make a grinding machine with their own hands. The reason for this question is quite simple: the high cost of serial grinding equipment, which not everyone can pay off if not used regularly. In order to make such equipment, you will need several main components: an electric motor, rollers and a reliable frame. Naturally, drawings of such a device or a photo of it would not be superfluous. Also at the end of the article you can watch videos on assembling a tape machine on your own.

The motor for belt grinding equipment is not difficult to find; it can be removed from an old one. washing machine. You will have to make the frame yourself; for this you can use a sheet of metal with dimensions 500x180x20 mm. One side of the frame should be cut very evenly, since it will be necessary to attach the platform on which the electric motor will be mounted to it. The platform for the electric motor should also be made of a sheet of metal with dimensions 180x160x10 mm. Such a platform must be secured to the frame very securely using several bolts.

Another version of the bed

The efficiency of a belt sanding machine directly depends on the characteristics of the electric motor that is installed on it. If you are planning to make a grinding machine with your own hands, then an electric motor with a power of 2.5–3 kW, developing about 1500 rpm, is quite suitable for you. In order for the sanding belt to move at a speed of 20 m/s when using such a motor, the drums must have a diameter of about 200 mm. What’s convenient is that if you choose an engine with these characteristics, you won’t need to make a gearbox for your grinding machine.

The drive shaft is connected directly to the electric motor shaft, and the second - driven - must rotate freely on an axis, which is installed in bearing units. In order for the abrasive belt to touch the surface of the workpiece more smoothly, the section of the frame on which the driven shaft is installed should be made with a slight bevel.

You can make shafts for a belt grinding machine with minimal financial costs from chipboards. Simply cut square blanks of 200x200 mm in size from such a plate, drill central holes in them and place them on the axle with a package with a total thickness of 240 mm. After this, all you have to do is grind the resulting package and make it into a round shaft with a diameter of about 200 mm.

Drawings and detailed analysis of some parts of a machine made of wood.

Wood belt sander (click to enlarge)

Table tilt adjustment mechanism Plate block Belt tensioner

During construction and repair work Men often need to process wood, stone or metal. For quality work It is advisable to purchase a belt sanding machine. But what to do when finances do not allow you to make such a purchase? To do this, it is enough to build a belt sanding machine with your own hands.

Purpose of a belt sanding machine

Wood is widely used in a wide variety of manufacturing organizations. Many different parts and products are made from wood. In order to properly process a wooden blank and give it the appearance of a finished product, it is customary to use various equipment, including belt sanders.

Belt grinding equipment is usually used on final stages production, when parts are subjected to finishing machining. Such devices are convenient to use in furniture production and different products made from wood for consumer use. Depending on the material used, belt sanders work with wood or metal.

The main purposes of using wood sanding machines are final alignment surfaces, bringing their roughness level to the required value, obtaining smooth and smooth surfaces for wood products and wood material before veneering or after coating with varnish and other finishing materials, removal of local irregularities in the form of depressions and elevations, peeling off burrs and removing local deposits of varnish and primer, deburring, internal grinding and grinding of curves.

Belt grinding machines for metal work with various materials and formats that are common in metalworking: plain and alloy steel, non-ferrous metals in the form of quadrangular, round and flat workpieces. Grinding machines allow efficient and effective minimal costs time to grind round timber and large diameter pipes.

Depending on the type of processing and type of feed, belt grinding machines are intended for:

for grinding curved surfaces with a free sanding belt;
for processing a flat surface with a fixed table, manual movement of the iron and table, as well as mechanized movement of the work table and manual movement of the iron;
for processing panel and block parts, their ends and side edges;
for intermediate sanding of paintwork.

Belt Sanding Machine Design

Belt grinding machines are produced by modern foreign and domestic producers in a wide range. Grinding machine prices vary widely. They also differ in possible performance and design. However, they also have something in common. They are united by the fact that absolutely all machines have an abrasive belt as a working element, which is most often connected into a ring and placed between rotating drums.

One drum is the master drum and the other is the slave drum. This means that the first of them is equipped with a mechanical transmission, which is most often based on a belt drive, through which torque is transmitted to it from an electric motor. Any belt sanding machine is designed in such a way that the speed of movement of the drive drum, and therefore the speed of movement of the abrasive belt, can be changed, providing different modes of surface treatment.

The abrasive belt can be positioned vertically or horizontally. In addition, equipment modifications are available for sale in which the working element is installed at a certain angle. The abrasive belt is mounted on a frame, on which the workpieces are usually located. Workpieces can be held by the operator manually or with the help of special devices that make the work easier for consumers and make the processing procedure more efficient and safe.

The machine table is made from metal sheets or thick boards. If the design provides for the table to be made of metal, then it will be possible to sharpen more complex products. The length of the working part of the belt grinding machine and the grinding belt itself primarily depends on the length of the products that will be sanded on the machine.

If the part has a shorter length than the working surface of the machine, then it will be much more convenient to process, and the processing will be of higher quality. For example, with a sanding belt length of 4.5 meters, you can easily process wooden workpieces that are 200 centimeters long.

Belt grinding machines are divided into equipment with a fixed and movable work table and devices with a free belt. A special group is wide-belt grinding machines, in which the caterpillar-shaped table is also a feeder. For machines with tables, the belt is placed horizontally; for designs with a free belt, it is installed in different ways.

Since the grinding process inevitably generates a lot of dust, all belt grinding machines are usually equipped with special powerful hoods that remove most of it during the technological process itself. Grinding machines are powered by an electric motor, which has a power of about 2.8 kilowatts. With motor high power The normal speed of the belt reaches 20 meters per second.

Abrasive belts for grinding machines

The cutting tool of belt sanding machines is a sanding belt, which consists of fabric or paper base and abrasive grains that are attached to it using adhesives. Abrasive belts are manufactured using two methods: mechanical and electrical. The first method consists of uniformly pouring abrasive grains onto a base that is covered with glue, and the second method occurs in electric field, which orients the grains upward with their sharpest edges to improve the cutting properties of the grinder.

Abrasive grains are poured onto the base in a bundle tightly or sparsely. The most effective is considered to be an abrasive belt with a sparse backfill, when the grains occupy less than 70% of the area, because wood dust generated during the grinding process is not able to get clogged between their grains. Natural minerals or artificial materials, which have high hardness, for example, green and black silicon carbide, white and normal monocorundum, as well as normal electrocorundum.

For the purpose of gluing grains, synthetic resins and hide glue are used. As a base, fabric such as calico and twill, or special grade paper is used. The size of the abrasive grains is indicated by a number that corresponds to the size of the sieve cells in which these grains are retained, and is displayed in hundredths of a millimeter.

If you are interested in how to make a belt sanding machine, then you should pay attention to the following sizes of grinding powders and abrasive grains and their classification: grinding grain - from 2000 to 160 microns, grinding powders - from 125 to 40 microns; micropowders - from 60 to 14 microns, very fine micropowders - from 10 to 3 microns.

Sanding paper is supplied to woodworking enterprises in sheets or rolls. On the non-working surface of the skin there is a marking with the specified characteristics of the skin and the manufacturer. For a belt sanding machine, skins are used in rolls and cut into strips of a certain length and width. The length of the cutting tool is determined depending on the method of its connection - lap or butt at an angle.

The ends are cut off when gluing end-to-end at an angle of 45 degrees and then glued onto a canvas lining with a width of 80 to 200 millimeters. At one end of the tape, when gluing with an overlap, the abrasive grains are removed with hot water over a distance of 80 to 100 millimeters, then the other end of the tape is applied to the exposed base lubricated with glue. Squeeze the joined ends and dry them when using special device or size press.

Sheet sandpaper is used for combined belt-grinding machines. For grinding discs It is customary to cut the skin in the form of a circle according to a template, the diameter of which is 60 - 80 millimeters larger than the diameter of the disk. Using a rectangular template, blanks are cut for the reel. After cutting, they have smooth edges without tears. The presence of unglued ends or seals when gluing tapes can cause premature rupture of the tape.

The skin is cut for wide-belt sanding machines into sheets according to a template made of plywood or aluminum sheet. The skin is cut in such a way that the edges are smooth and the difference in the length of the side edges is no more than 1 millimeter. One of the beveled edges is cleaned, removing abrasive to a width of 20 millimeters. Cleaned edge and longitudinal edges pasted over with a strip of tracing paper, which has a width of 40 millimeters, which protrudes beyond the edge of the skin by about 10 millimeters.

Lubricate the beveled edge with tracing paper with glue and leave it in the air, depending on the viscosity and type of glue. Then the beveled edges are joined and a strip of sandpaper is applied to the joint, the joint is compressed and held in a press. It is customary to hang finished endless belts on special brackets and keep them for at least a day in a dry room before installing them on a grinding machine.

Operating principle of a belt grinding machine

A belt sanding machine consists of a table top with a work table for mounting the cutting tool. This table is fixed in different positions relative to the tabletop. The material for the countertop is usually laminated Chipboard thickness 25 millimeters. The worktable on rollers is moved manually or laterally by a mechanical drive along round guides that are attached to supports.

Above the table there is a working belt mounted on non-drive and drive pulleys. The sanding belt is tensioned and adjusted using a screw device with a pneumatic cylinder. Double belt sanders have two identical sanding tools that are placed in series on a bed and have sanding belts that move towards each other.

Grinding is done at lateral movement working table and longitudinal movement of a short iron, which presses the tape to the material being processed. The sanding belts are driven by an electric motor via a belt drive. The waste generated during grinding is collected by a dust collector, which is connected to the exhaust network.

When assigning a grinding mode, it is recommended to select the grain size of the sandpaper, the feed speed and the pressing force of the belt to the product based on the specific roughness and properties of the material being processed. The grain size of the skin is usually chosen depending on the hardness of the materials being processed and the required surface roughness. The clamping force and feed speed are interdependent quantities. With little force and high feed speed, some areas of the surface may not be sanded; with high pressure and low feed, burns and blackening of the material are possible.

Before installing the tape, check the quality of its gluing. Do not use incorrectly glued or torn sanding belts with uneven edges. Using the handwheel, you can reduce the distance between the pulleys and put on the belt. The gluing area is placed so that the outer end of the seam on the abrasive side is directed against the working movement of the sanding belt.

The belt tension can be adjusted by moving the tension roller for the belt grinder or the non-drive pulley. It is not advisable to tighten the tape too much, as this will cause it to break. But the sanding belt, with low tension, slips along the pulleys and heats up very quickly. The tension force is set depending on the strength of the base of the cutting tool and is determined by the arrow of its deflection with slight pressure on it.

How correctly the belt runs can be checked by turning the pulley manually or briefly turning on the electric motor. When the belt slips, the pulley axis is turned by a handle at a small angle and secured with a locking device. After setting up the belt grinding machine, the dust suction system is turned on, a trial processing of the parts is carried out and their quality is checked.

A manual feed belt grinder can be operated by one worker. By moving the product relative to the cutting tool in the longitudinal direction and rotating the part around its axis, the operator sequentially brings into contact with the tape all areas that form the surface to be processed. If you slow down or move carelessly, sanding may occur.

It is customary to grind individual sections of a part in several passes. High-quality leveling can be achieved by properly regulating the pressure applied to the handle of the iron and the speed of movement of the table and iron. The pressure must be reduced as you approach the edges to prevent them from being sanded off. To increase the quality and productivity of grinding, small bars are placed on the table in a row, several pieces at a time.

Belt grinding machines with mechanical feed of products are serviced by two operators. One of them places the part on the conveyor, orients it along the width of the work table and directs the product under the clamping elements of the machine. When being picked up by a conveyor, parts must not be moved laterally.

It is not allowed to feed into the machine workpieces that have unequal thickness and parts with gross surface defects. The feed rate and pressure of the clamping beam, as a rule, are not regulated during processing. The second operator receives finished parts and ensures that unacceptable edge rounding and sanding does not occur.

Making a Belt Sanding Machine

The price of belt grinding machines from an industrial manufacturer is quite high, so when they are used infrequently, craftsmen involuntarily think about whether to buy the equipment or not. An alternative to buying an expensive machine is to assemble it yourself. The main parts of the machine are the frame, rollers and engine.

The motor can be removed from an old washing machine. Cut the frame from thick iron measuring 500 by 180 by 20 millimeters. Cut one side straight milling machine for metal, it is required to attach the platform with the motor. The dimensions of the working platform are approximately 180 by 160 by 10 millimeters. Make markings and drill three holes in the end of the evenly cut frame. It is necessary to tighten the platform to the frame with three bolts.

Remember that the longer the work table is, the more options you will have when choosing a technological method for grinding and processing the product. If the length of the workpiece is less than or equal to the length of the work table, then you can achieve a perfect grind much easier than when moving a large workpiece.

The engine must be placed tightly on the frame. It should have a power of approximately 2.5-3.0 kW and a rpm of about 1500. If you choose a sanding belt speed of approximately 20 m/s, then the diameter of the drums should be about 200 millimeters. Thus, if the engine speed is sufficient, a gearbox for the grinding machine is not required.

One of the two drums will play the role of a leader, which should be firmly fixed to the engine shaft, and the other tensioner should rotate freely around fixed axis on bearings. The table on the side of the driven drum should have a certain bevel, which will ensure smooth contact of the sanding belt with the surface of the work table, this is especially true for a glued joint.

You can make a tension drum and a drum that guides the sanding belt from chipboard. To do this, you need to cut blanks from the slab with overall dimensions of 200 by 200 millimeters and assemble a package of 240 millimeters from them. Square tiles or a package of them should be folded on an axis and machined to a diameter of about 200 millimeters.

Remember that in the center the diameter of the drum should be 2-3 millimeters larger than at the edges. With a similar surface geometry, the flexible sanding belt will be located in the middle of the drum. Optimal width tape is 200 millimeters. From a roll of emery cloth that is 1 meter wide, you can easily glue 5 similar tapes together.

The cutting tool must be glued end-to-end, with a thin, dense material, for example, a tarpaulin, placed underneath. It is recommended to use the highest quality glue you can get. To the skating rinks in mandatory stretch the rubber, the width of which reaches 30 millimeters. Rubber can be taken from the inner tubes of a moped or bicycle.

On a homemade belt sanding machine, in addition to grinding wooden products, for which it is actually intended, it is very convenient to sharpen tools with cutting surfaces - chisels, knives, axes, pruners. Another advantage of this grinding machine is the ability to work with parts that have a curved surface - for this you need to grind the workpiece reverse side working tape.

Wood is a rather capricious material. Therefore, to give wooden structures an aesthetic shape, prepare their surface for further processing by sanding the wooden surface. Window frames, vents, doors, and moldings are subjected to grinding.

Making the surface smooth is done using grinding machines. They allow you to level the surface of the workpiece and eliminate all roughness ranging in size from 0.02 to 1.25 microns.

Types of grinding machines

Wood sanding machines are divided into the following types:

design features;
the nature of the tasks being solved;
processing accuracy;
permissible geometric dimensions of processed parts;
power of installed engines;
manufacturer ratings;
cost with a set of attached equipment.

Modern manufacturers present three types of design of such machines: disk, belt, cylinder. Each of these species has its own highly specific subspecies. For example, they are available in the following versions:

narrow-belt (allow grinding of wooden structures with complex geometric shapes);
units equipped with a fixed table (capable of processing only wooden workpieces with flat surfaces rectangular shape);
machines equipped with a freely moving table (they are used for grinding large-sized wooden structures - doors, panels, door slopes).

The nature of the tasks to be solved determines the classes of this equipment. The main classes (sometimes called models) are:

belt grinding machines;
vibrating tools such as delta grinders;
disc-type grinding machines (orbital and eccentric);
specialized angle grinders;
combined type grinding systems.

Despite such a variety of ready-made factory tools, home craftsmen prefer to develop and assemble a wood grinding machine with their own hands to carry out simple grinding operations.

Principle of operation

The basis of the operation of a grinding machine belt type The principle of counter-movement of an abrasive belt located on two rotating drums and the processed wooden part is laid down. Both drums are located at a certain distance from the desktop surface. To ensure the required grinding quality, the following parameters must be correctly taken into account:

size (number) of abrasive applied to the tape;
the tension force of the belt on the rotating drums;
the speed of its movement;
the force of pressure on a moving wooden part.

Incorrect selection of these parameters significantly degrades the quality of grinding. For example, if the pressure on the workpiece is insufficient or the rotation speed of the drive drum is too high, some places on the workpiece will remain unprocessed, that is, they will not be polished. On the contrary, if there is excessive pressure from the belt on the surface and insufficient speed of the belt, burns and changes in the color of the wood are possible. Therefore, when assembling a grinding machine with your own hands, it is necessary to provide for the possibility of adjusting these parameters.

Design features of the machine

The design of the machine depends on the selected principle of processing the part. If the principle of belt grinding is chosen, then the machine includes the following elements: motor, two shafts (drive and driven), housing, (bed), working surface, abrasive belt.

In so-called disc-type machines, rotating discs with fixed abrasive wheels are used on a frame with a motor as a grinding device.

Application areas of the machine

Each of the manufactured machines performs a predetermined list of technological operations.

The drum-type system produces high-quality sanding of flat wood pieces. Processing of chipboard, OSB or MDF, including those covered with veneer, is allowed.

Processing of large, long, non-standard wooden wood products (for example, molded structures) is carried out using profile grinding equipment. Finished workpieces are fed to the grinding unit via a conveyor chain.

To grind the surface of wooden products that have a complex geometric shape (decorative frames, artistic products), belt sanding machines equipped with a freely moving table are used.

DIY grinding machine

Desire to make your own wooden structures I am always faced with the need to equip my workshop with sawing and grinding machines. Modern manufacturers produce them in a wide range. Such machines have good performance and high reliability. The most important and quite significant drawback is their high cost.

Therefore, many craftsmen try to assemble a grinding machine from existing components. The most experienced ones try not to limit themselves to a machine capable of performing only one function; they immediately try to assemble universal machine, capable of performing several functions: cutting wooden blanks, grinding followed by polishing, removing old coatings and preparing surfaces for renovation.

This is possible because the basis of any homemade machine consists of a frame on which are mounted: an engine, driving and driven drums, a set additional equipment(saw blade, milling cutter, grinding wheels, etc.).

Calculation of grinding machine power

Before you begin assembling the machine, you must calculate its power. To correctly make such an assessment, it is necessary to determine the following parameters:

power consumed by the electric motor;
rotation speed of the selected engine;
the area of contact of the entire surface of the part with the moving abrasive belt;
grinding ratio;
coefficient of friction between the back side of the belt used and the surface of the drums.

Based on data on these parameters, the power of the future unit can be determined.

How to make a belt sander

The basis of the machine is a powerful frame that can withstand the weight of all equipment and perform the function of damping the resulting vibration. The frame of the bed is best fastened by welding. A plate is attached to the top. Chipboard with a thickness of at least 22 mm is chosen as such a plate.

An electric motor is mounted on the frame. The engine power must be no lower than the calculated one. The number of revolutions must be at least 1500 rpm. A gearbox is attached to the anchor to transmit rotation to the drive drum. The required diameter directly depends on the engine speed. It determines the speed of the belt at the moment of friction against the surface of the part.

The following relationships can be given as an example. When the belt speed is 20 m/sec, the diameter should be 20 cm. To prevent the slipping effect, rubber covers are placed on the drums. It is more expedient to make the platform for installing the drums at a slight slope. This will create smooth contact of the tape with the surface being treated while moving.

If you plan to process parts made of different types of wood, it is advisable to provide the possibility of changing the rotation speed of the drum. The above technique shows that it is quite easy to assemble a grinding machine with your own hands.

What to make the bed out of

The frame to which all other elements of the machine are attached is a powerful bed. It must have a large margin of safety and have good weight and size characteristics. It is made from sheet steel more than 5 mm thick.

The most acceptable sizes homemade bed The following dimensions are considered: 500x180x20 millimeters. For a bed of this size optimal sizes the working platform is considered to be 180x160x10 millimeters.

For the convenience of further work, it is necessary to mark the work site. Three holes are made for its fastening. Then it is secured to the frame with three bolts.

Selecting and installing a motor for the machine

Calculations and operating experience of this type of units show that the engine must have a power of at least 2.5 kW. The shaft rotation speed must be 1500 rpm or more. The speed of movement of the abrasive belt largely depends on the engine rotation speed. This seriously affects the quality of processing. In turn, the speed of the belt affects the diameter of the drums.

As a finished device, you can use the motor that is installed on washing machines. You can also select an engine from other household units, for example, a powerful pump or other device suitable in terms of power and speed.

Master and slave drums

The drive drum is firmly fixed to the electric motor pulley. The driven drum is fixed on a separate axis. To ensure its free rotation, bearings are attached between the shaft and the drum.

DIY sanding belt

Abrasive belts for such machines have a fabric base. Calico or a fabric of similar density is used as a base. Abrasive chips are applied to the surface of the material on one side using special glue. Depending on the grain size of this crumb, it is divided into large, medium, small and zero.

In principle, such a tape can be made independently. Select the required fabric and apply abrasive powder of the required fraction to it. By applying glue to the surface of the material and sprinkling it with this powder, you can obtain a sanding belt of the required size. However, it should be recognized that modern industry produces such a wide range of such Supplies, that it is better to use the factory one.

Sanding machine from a hand sander

Very often, to carry out simple grinding operations, homemade wood grinding machines are made using ready-made grinding machines.

A mounting system for a grinding machine is being manufactured. It is mounted on a pre-prepared frame. Grinding wheels intended for processing wooden workpieces are attached to its shaft. Instead of such a machine, you can use an ordinary one electric drill. This design allows sanding of simple wooden parts of limited size.

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